Protestant Catholic Jewish Other
Democrat 0.35 0.10 0.03 0.02
Republican 0.27 0.09 0.02 0.01
Independent 0.05 0.03 0.02 0.01
1. The table above gives the probabilities of combinations of religion and political parties in a city in the
United States. What is the probability that a randomly selected person will be a Protestant and at the same
time be a Democrat or a Republican?
2. The possible values of x in a certain continuous probability distribution consist of the infinite number of
values between 1 and 20. Solve for P(x = 4).
3. A credit card company decides to study the frequency with which its cardholders charge for items from
a certain chain of retail stores. The data values collected in the study appear to be normally distributed with
a mean of 25 charged purchases and a standard deviation of 2 charged purchases. Out of the total number
of cardholders, about how many would you expect are charging 27 or more purchases in this study?
4. A continuous probability distribution represents a random variable
A. that’s best described in a histogram.
B. having outcomes that occur in counting numbers.
C. that has a definite probability for the occurrence of a given integer.
D. having an infinite number of outcomes that may assume any number of values within an interval.
5. From an ordinary deck of 52 playing cards, one is selected at random. What is the probability that the
selected card is either an ace, a queen, or a three?
6. Let event A = rolling a 1 on a die, and let event B = rolling an even number on a die. Which of the
following is correct concerning these two events?
A. Events A and B are mutually exclusive.
B. On a Venn diagram, event A would overlap event B.
C. Events A and B are exhaustive.
D. On a Venn diagram, event B would contain event A.
7. The area under the normal curve extending to the right from the midpoint to z is 0.17. Using the
standard normal table on the textbook’s back endsheet, identify the relevant z value.
8. Each football game begins with a coin toss in the presence of the captains from the two opposing teams.
(The winner of the toss has the choice of goals or of kicking or receiving the first kickoff.) A particular
football team is scheduled to play 10 games this season. Let x = the number of coin tosses that the team
captain wins during the season. Using the appropriate table in your textbook, solve for P(4 ≤ x ≤ 8).
9. What is the value of ?
10. The Burger Bin fast-food restaurant sells a mean of 24 burgers an hour and its burger sales are
normally distributed. The standard deviation is 6. What is the probability that the Burger Bin will sell 12 to
18 burgers in an hour?
11. Approximately how much of the total area under the normal curve will be in the interval spanning 2
standard deviations on either side of the mean?
12. For each car entering the drive-through of a fast-food restaurant, x = the number of occupants. In this
study, x is a
A. discrete random variable.
B. joint probability.
C. continuous quantitative variable.
D. dependent event.
13. A breeder records probabilities for two variables in a population of animals using the two-way table
given here. Given that an animal is brown-haired, what is the probability that it’s short-haired?
Short-haired 0.06 0.23
Shaggy 0.51 0.20
14. If event A and event B are mutually exclusive, P(A or B) =
A. P(A) – P(B).
B. P(A) + P(B).
C. P(A + B).
D. P(A) + P(B) – P(A and B).
15. In the binomial probability distribution, p stands for the
A. number of trials.
B. number of successes.
C. probability of failure in any given trial.
D. probability of success in any given trial.
16. The probability of an offender having a speeding ticket is 35%, having a parking ticket is 44%, having
both is 12%. What is the probability of an offender having either a speeding ticket or a parking ticket or
End of exam
17. The Burger Bin fast-food restaurant sells a mean of 24 burgers an hour and its burger sales are
normally distributed. If hourly sales fall between 24 and 42 burgers 49.85% of the time, the standard
deviation is _______ burgers.
18. An apartment complex has two activating devices in each fire detector. One is smoke-activated and has
a probability of .98 of sounding an alarm when it should. The second is a heat-sensitive activator and has a
probability of .95 of operating when it should. Each activator operates independently of the other. Presume
a fire starts near a detector. What is the probability that both activating devices will work properly?
19. Tornadoes for January in Kansas average 3.2 per month. What is the probability that, next January,
Kansas will experience exactly two tornadoes?
20. Which of the following is correct concerning the Poisson distribution?
A. The mean is usually smaller than the variance.
B. The event being studied is restricted to a given span of time, space, or distance.
C. Each event being studied must be statistically dependent on the previous event.
D. The mean is usually larger than the variance